1. Field of the Invention
Embodiments of the invention relate to the field of semiconductor, and more specifically, to semiconductor packaging.
2. Description of Related Art
Advanced flip chip packaging technologies have been actively developed in recent years to meet the requirements for high performance and reduced form factor in a variety of applications such as consumer and wireless products. One phase in a typical packaging process is the formation of contacts or interconnects such as solder balls or bumps on the substrate.
Existing methods for substrate bumping have a number of drawbacks. One technique uses a stencil and a squeegee to apply the solder paste. This technique often causes solder past lift-off with the stencil when the solder resist openings are small, leaving foreign material on the solder resist, as well as creating other alignment issues. Another technique uses disposable mask technology to enable solder paste printing. In this technique, a dry film resist (DFR) mask is used as a sacrificial stencil layer on top of the SR. This DFR mask replaces the typical metal stencil for solder paste printing and burns away during the solder reflow process. However, there may be DFR residues left over on the SR surface. Failure to completely remove the residues may lead to contamination, yield loss, problems in test and assembly, reliability, and undesirable performance issues at the bump side, such as epoxy underfill delamination.